JP2017170905A - Crosslinked polypropylene foam and laminates made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide crosslinked polypropylene and polypropylene-polyethylene foams that maintain desired thermoforming and performance requirements and exhibit improved anchorage to support layers such as thermoplastic polyolefin (TPO), and to provide a laminate having the foams supported to the support layers.SOLUTION: A laminate comprises a polypropylene polymer, an elastic component, and a foaming agent, in which as the elastic component, the laminate comprises 10 pts.wt of crystalline olefin-ethylene butylene-crystalline olefin based on 100 pts.wt of the total weight of a resin component and the elastic component and comprises 80-90 pts.mass of the polypropylene polymer based on 100 pts.mass of the total mass of the resin component and the elastic component. The laminate has blister rating of 1-2, density of 85-125 kg/m3, an unaged peel tear strength of at least about 34 N and a heat-aged peel tear strength of at least about 28 N when laminated on a support layer. The laminate includes a foam composition laminated on the support layer, in which in the foam composition, the elastic component is blended with the polypropylene polymer.SELECTED DRAWING: None

Description

(Cross-reference of related applications)
This application is related to provisional patent application 61 / 487,092 filed on May 17, 2011, 61 / 508,232 filed on July 15, 2011, and 61/487, filed on December 12, 2011. No. 569,422, the entire disclosure of which is hereby incorporated by reference.

  The present disclosure relates to cross-linked polypropylene foams and polypropylene-polyethylene foams that have improved adhesion to support layers such as thermoplastic polyolefin (TPO) while maintaining desirable thermoforming and performance requirements.

  Physically cross-linked closed-cell polypropylene foams and polypropylene-polyethylene blend foams are commercially produced and used in a variety of applications. One such application is automotive interior trim. In automotive interiors, door panels, instrument panels, center consoles, front seat armrests and other interior components may include a layer of polypropylene foam. The foam is usually just behind the surface of these trim parts. The surface layer of these trim parts is often a plastomer, elastomer plastomer or elastomeric TPO.

  Various manufacturing techniques are used for manufacturing these automobile interior trim parts. For example, some manufacturers use TPO-polypropylene foam bilayer laminates that are vacuum molded and simultaneously bonded to a plastic substrate to produce an interior trim panel.

  Usually, these TPO-polypropylene bilayer laminates are manufactured with a third party laminator. In some cases, the laminator extrudes molten TPO directly onto the polypropylene foam, compresses the material and passes it through a “nip roll” to bond the TPO of the support layer and the foam, thus creating a two-layer laminate. . In another case, after the sheets of TPO are individually manufactured by a laminator, the TPO sheets and / or foam are exposed to heat and pressure to bond the sheets and foam, thus creating a two-layer laminate.

The adhesion and adhesive strength between the support layer / TPO and the polypropylene foam are important. Unsatisfactory performance results in unfavorable performance characteristics. For example,
1) When a two-layer laminate is vacuum-formed on a plastic substrate, the two-layer laminate may be heated to 180 to 210 ° C. Insufficient adhesion can cause TPO to blister and separate from the foam at high temperatures.
2) When using a TPO-foam two-layer laminate for an instrument panel, the two-layer laminate needs to be torn cleanly along the seam line containing the airbag that breaks through the two-layer laminate during deployment. There is. Insufficient adhesion with TPO can cause the foam and TPO in the two-layer laminate to separate in an undesirable manner during deployment.

A foamed composition comprising about 50 to about 95 parts by weight of at least one polypropylene polymer having a density of about 85 to about 125 kg / m ³ , having a blister rating of 1 to 2, and aging when laminated to a support layer Compositions are provided wherein the previous peel tear strength is at least about 34N and the peel tear strength after heat aging is at least about 28N.

  Moreover, the laminated body which laminated | stacked the said foaming composition on the support layer is further provided.

A foamed composition comprising about 50 to about 95 parts by weight of at least one polypropylene polymer having a density of about 50 to about 85 kg / m ³ , having a blister rating of 1 to 2, and aging when laminated to a support layer Further provided is a composition having a previous peel tear strength of at least about 26 N and a post-heat aging peel tear strength of at least about 19 N.

  There is further provided a laminate in which the foamed composition is laminated on a support layer.

A foamed composition comprising from about 30 to about 50 parts by weight of at least one polypropylene polymer having a density of about 50 to about 85 kg / m ³ , having a blister rating of 1 to 2, and aging when laminated to a support layer Further provided is a composition having a previous peel tear strength of at least about 17N and a heat tear age peel tear strength of at least about 15N.

  There is further provided a laminate in which the foamed composition is laminated on a support layer.

  The following description sets forth details regarding selected representative aspects of the present disclosure. Also, various equivalents may be used in place of specific elements of the methods, compositions and laminates described herein without departing from the spirit and scope of the present disclosure as set forth in the appended claims. I hope you understand. Moreover, all publications cited herein, such as but not limited to patents and patent applications, are incorporated by reference as if fully set forth.

  The range specified in this specification (for example, 50 to 95%) includes a value (for example, 50 and 95%) that defines the upper and lower limits of the described range, and all discrete values within the range (for example, 51%). 51.1,%, 52%, etc.) and all discrete subranges within the range (eg 60% -70%, 68% -78%, 85% -90%).

  Also, those skilled in the art agree with probability theory and statistics, and in some cases, a composition equivalent to the composition described in this specification can be explained by normal fluctuations that can be explained by a Gaussian distribution. It will be understood that one or more characteristics may be different from the exact values set forth in the specification. Such compositions have values that are considered “approximately” a predetermined value. Further, those skilled in the art will find that preparations of olefin block copolymers or polypropylene-based polymers with controlled block chain distribution that are useful in the compositions, laminates or methods of the present invention may contain small amounts of antioxidants or other materials. It will be understood that (usually 0% to 1% of the weight of such preparations) may be included. Accordingly, those skilled in the art will understand this when preparing an amount of such a preparation that is "approximately" a specific value.

The selected properties described herein are defined and measured as follows.
The “melt flow index (MFI)” value of the polymer is defined according to ASTM D1238, with a plunger of 2.16 kg at 190 ° C. for polyethylene and polyethylene-based materials and 230 ° C. for polypropylene and polypropylene-based materials. Use and measure for 10 minutes. For resins with a relatively high melt flow, the test time may be reduced. MFI is sometimes called “resin melt flow rate”.

The “melting temperature” (T _m ) of a polymer or a polymer foam composition comprising the polymer is measured by differential scanning calorimetry (DSC). The melting temperature is determined as follows. First, a sample of 10-15 mg of polymer or polymer foam composition is heated from room temperature to 200 ° C. at 10 ° C./min. Next, the sample is cooled from 200 ° C. to room temperature at a rate of 10 ° C./min, and then second heating is performed from room temperature to 200 ° C. at 10 ° C./min. The endothermic peak value specified during the second heating is defined as the melting temperature.

  The “thickness” of the foam sheet is measured according to JIS K6767.

  The “density” of the foam sheet is measured according to JIS K6767 using a partial density or “total” density rather than a “core” density.

  The “laminated surface density” of the foamed sheet is measured by slicing 0.45 to 0.60 mm of the surface of the foamed sheet that contacts the TPO. According to JIS K6767, the thickness and density of the sliced foamed layer are measured.

  The “total crosslinking degree” is measured according to the “Toray Gel Fraction Method” in which the non-crosslinking component is dissolved with a tetralin solvent. A non-crosslinked product is dissolved in tetralin, and the degree of crosslinking is expressed in terms of mass percent of the crosslinked product.

  The equipment used to measure the rate of polymer cross-linking is 100 mesh (wire diameter 0.0045 inch), 304 stainless steel bag, numbered wires and clips, Miyamoto constant temperature oil bath equipment, chemical balance, ventilation hood, gas burner, high temperature oven And a stainless steel container (3 pieces) with an electrostatic gun and a 3.5 liter wide-mouthed lid. As reagents and materials, tetralin polymer solvent, acetone and silicone oil are used.

  Specifically, the mass of an empty wire mesh bag is measured and the mass is recorded. Weigh about 2 grams to about 10 grams ± about 5 milligrams for each sample and transfer to a wire mesh bag. Record the weight of the wire mesh bag and the sample (usually in the form of foam cuttings). Each bag is attached to the corresponding numbered wire and clip.

  When the temperature of the solvent reaches 130 ° C., the bundle (bag and sample) is immersed in the solvent. Shake the sample up and down about 5 or 6 times to shake off the bubbles and moisten the sample sufficiently. The sample is attached to a stirrer and stirred for 3 hours so that the foam dissolves in the solvent, and then the sample is cooled in a fume hood.

  The sample is washed by shaking it up and down 7 or 8 times in the first acetone container. The sample is washed again with a second acetone wash. The washed sample is once again washed as described above in a third unused acetone container and then suspended in a fume hood for about 1 to about 5 minutes to evaporate the acetone.

  The sample is then dried in a drying oven at 120 ° C. for about 1 hour. Allow the sample to cool for a minimum of about 15 minutes. Weigh the wire mesh bag with an analytical balance and record the mass.

  Subsequently, the degree of crosslinking is calculated by the formula: 100 × (C−A) / (B−A). A = Empty wire mesh bag mass, B = Wire mesh bag mass + foamed sample before tetralin immersion, C = Wire mesh bag mass + dissolved sample after tetralin immersion.

  The “laminated surface cross-linking degree” is measured by slicing 0.45 to 0.60 mm of the surface of the foam sheet that is in contact with the support layer / TPO. The amount of the cross-linked product in the slice piece of 0.45 to 0.60 mm is quantified using the “Toregel fraction method”.

  “Compressive strength” is measured according to JIS K6767. Stack 50 × 50 mm pre-cut foam to 25 mm and compress to 75% of the original stacked height at a speed of 10 mm / min. After maintaining the compressed state for 20 seconds, the compression strength is recorded.

  “Blister rating” is an optional rating of 1-5 that represents the amount and extent of TPO delamination after the support layer / TPO-foam bilayer laminate has been exposed to 160 ° C. for 10 minutes. “1” indicates that there is no delamination, and “5” indicates that delamination is severe.

  “Peel tear strength” is defined and measured according to TSL5601G. A strip-shaped support layer / TPO-foam bilayer laminate of 25 mm × 150 mm is pulled apart in both the machine direction and the lateral (width) machine direction at 200 mm / min.

  The disclosed foam composition is obtained by blending a composition of the main polymer resin (s) with a crosslinking monomer and a chemical blowing agent.

  The foam composition may contain about 30 to about 95 parts by weight, preferably about 40 to about 90 parts by weight of polypropylene and / or polypropylene-based polymer.

  As used herein, the value of “parts by mass” refers to the main polymer resin (impact polypropylene homopolymer (impact) of components (such as copolymers in the foam composition) present in a given composition (foam composition, etc.). Impact hPP), polypropylene random copolymer (PP RCP), linear low density polyethylene (LLDPE), crystalline olefin-ethylene butylene-crystalline olefin (CEBC), very low density polyethylene (VLDPE) and ethylene / α- It refers to the mass relative to the total mass of the olefin copolymer (OBC).

  The main polymer resin preferably has a specific MFI of about 0.1 to about 15 g / min at 230 ° C. and 2.16 kg as measured by ASTM D1238 for impact resistant hPP, PP RCP and CEBC. The main polymer resin preferably has a specific MFI of about 0.1 to about 15 g / min at 190 ° C. and 2.16 kg as measured by ASTM D1238 for LLDPE, CEBC, VLDPE and OBC.

  As described above, MFI is a measure of the flow characteristics of the polymer and is an indicator of the molecular weight and processability of the polymer material. If the MFI value is too high, it leads to a low viscosity, making it difficult to perform the extrusion process sufficiently. Problems associated with MFI values that are too high include low pressure during melt processing, problems with calendering and sheet thickness profile setting, low cooling viscosity due to low melt viscosity, low melt strength And / or mechanical problems. Problems with MFI values that are too low include high pressure during melt processing, difficulty in calendering, sheet quality and profile problems, and high processing temperatures that may cause the risk of decomposition and activation of the blowing agent. Etc.

The MFI range is important for the foaming process because it affects the viscosity of the material and the viscosity affects the melt strength and roughness of the material. The inventors believe that there are several reasons why a particular MFI value is very effective in the foam composition of the present invention. A material with a low MFI has a long molecular chain length and creates more energy required for the chain to flow when stressed, so some physical properties can be improved. In addition, the longer the molecular chain (M _w ), the larger the crystallized body that can be crystallized by the chain, and thus the stronger the strength due to intermolecular bonds. However, if the MFI is too low, the viscosity will be too high. In contrast, materials with high MFI values have short chains. During the material of higher predetermined amount of MFI values therefore, MFI is compared to a low material, a rotatable rotation (polymer T _g, that is, the rotational etc. occurs at a temperature above the glass transition temperature) of the area necessary for Therefore, there are more chain ends that can create a free volume at the microscopic level. This increases the free volume and facilitates flow under stress. In order to properly balance these characteristics, the MFI should be within the above range.

  During preparation of the foam composition, the main polymer resin is blended and mixed with the crosslinking monomer, and the properties of the foam composition are modified or improved by changing the degree of crosslinking. The degree of crosslinking is determined according to the “Toray gel fraction method” in which the non-crosslinked component is dissolved in the tetralin solvent as described above.

  As the crosslinking monomer, commercially available difunctional, trifunctional, tetrafunctional, pentafunctional and higher polyfunctional monomers are suitable. Such crosslinking monomers are available in liquid, solid, pellet and powder form. Examples include, but are not limited to, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, Acrylate or methacrylate compounds such as tetramethylol methane triacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate; allyl esters of carboxylic acids (trimellitic acid triallyl ester, pyro Meritic acid triallyl ester, oxalic acid diallyl ester, etc.); cyanuric acid such as triallyl cyanurate, triallyl isocyanurate or allyl ester of isocyanuric acid; N-phenylmaleimide, N, N′-m-f Maleimide compounds such as two bismaleimide phthalic acid Jipuropagiru, compounds having two or more triple bonds, such as Jipuropagiru maleic acid; divinylbenzene. The bifunctional liquid crosslinking monomer divinylbenzene (DVB) having a purity of about 80% is preferably about 0.1 to about 7.5 percent unit resin (PPHR), most preferably about 2.5 to about 3. It may be used in an amount of 75 PPHR. That is, the foam composition preferably comprises about 0.08 to about 6.0 PPHR, most preferably about 2.0 to about 3.0 PPHR DVB.

  Further, such crosslinking monomers may be used alone or in combination. Importantly, crosslinks can be generated by a variety of techniques and can be formed between molecules of different polymer molecules or within molecules between portions of the same polymer molecule. Such techniques include providing a cross-linking monomer separately from the polymer chain, or providing a polymer chain that incorporates a cross-linking monomer that contains a functional group that can form a cross-link or can be activated upon activation. The method of doing is mentioned.

The blended composition is usually also mixed with a thermally decomposable chemical blowing agent and / or blowing agent. In general, there are no restrictions on the type of chemical blowing agent. Examples of chemical foaming agents include azo compounds, hydrazine compounds, carbazides, tetrazoles, nitroso compounds, carbonates, and the like. Chemical foaming agents may be used alone or in combination. As the chemical foaming agent, azodicarbonamide (ADCA) is preferably used. Importantly, ADCA molecules typically thermally decompose during the expansion or foaming process. Examples of thermal decomposition products of ADCA include nitrogen, carbon monoxide, carbon dioxide, and ammonia. ADCA pyrolysis usually occurs at temperatures of about 190 to about 230 ° C. By adjusting the amount of the chemical blowing agent, the partial density of the resulting foamed composition can be adjusted. The allowable amount of foaming agent for obtaining the desired foam partial density can be easily determined. Chemical blowing agents are generally used in amounts of about 2.0 to about 25.0 parts by weight, depending on the required density. For azodicarbonamide, about 4.0 to about 8.0 parts by weight is preferred to obtain a foam partial density of 67 kg / m ³ .

  When the difference between the decomposition temperature of the thermally decomposable blowing agent and the melting point of the resin blend is large, a catalyst for decomposing the blowing agent may be used. Examples of the catalyst include, but are not limited to, zinc oxide, magnesium oxide, calcium stearate, glycerin, urea and the like.

  The foam composition may further contain additives that are compatible with the production of the disclosed foam composition. General additives include, but are not limited to, organic peroxides, antioxidants, lubricants, heat stabilizers, colorants, flame retardants, antistatic agents, nucleating agents, plasticizers, antibacterial agents, Examples include bactericides, light stabilizers, UV absorbers, antiblocking agents, fillers, deodorants, thickeners, bubble size stabilizers, metal deactivators and combinations thereof.

  Each component of the foam composition may be mechanically premixed if desired for easy dispersion. For such premixing, a Henschel mixer is preferably used. If the crosslinking monomer or other additive is a liquid, the monomer and / or additive can be added from the feed port of the extruder or the vent port of the vented extruder instead of being premixed with the solid components.

  After blending in a temperature range lower than the decomposition temperature of the thermally decomposable foaming agent, the components of the mixed foaming composition including the crosslinking monomer and the chemical foaming agent are melted, and the single screw extruder, twin screw extruder, Banbury Kneading with a kneading apparatus such as a mixer, a kneader mixer or a mixing roll. Thereafter, the obtained melted preparation is usually formed into a sheet-like material (sheet, film, web, etc.). Preferably, the sheet material is extruded with a twin screw extruder. Another method for forming a sheet-like material is the use of calendering.

  The melting temperature, kneading temperature and / or calendering temperature is preferably at least about 10 ° C. below the foaming agent decomposition start temperature. If this temperature is too high, the thermally decomposable foaming agent may decompose during kneading, which typically results in undesired premature foaming. The lower limit temperature for kneading and / or calendering is the melting point of the polypropylene resin in the composition (the higher melting point when two types of polypropylene resins are used). By kneading or calendering the composition between these two temperatures, once the sheet material is foamed, a regular cell structure and a flat foam surface are obtained.

  Next, the sheet material is irradiated with ionizing radiation at a predetermined irradiation dose to crosslink the composition, thereby obtaining a crosslinked sheet.

  The foamed composition may contain crosslinks produced by any known method such as ionizing radiation exposure at a predetermined irradiation dose, crosslinks with organic peroxides or silanes. When irradiated with ionizing radiation, a foam sheet comprising the disclosed composition having an excellent appearance and substantially uniform bubbles is obtained. Previously, when preparing such foam sheets with a composition comprising polypropylene (one or more) as the main component, it was not possible to obtain a sufficient degree of crosslinking with ionizing radiation. The method and composition of the present disclosure solves this problem. That is, by adding a crosslinking monomer in the method and composition of the present disclosure, polypropylene (one or more types) can be sufficiently crosslinked with ionizing radiation.

  Ionizing radiation includes, but is not limited to, alpha rays, beta rays, gamma rays, and electron beams. Among these, an electron beam having substantially uniform energy is preferably used for preparing the foamed composition of the present disclosure. The irradiation time, the number of times of irradiation, and the acceleration voltage when irradiating the electron beam can vary greatly depending on the intended degree of crosslinking and the thickness of the sheet-like material, but are generally about 10 to about 500 kGy, preferably about 20 to about 300 kGy. More preferably, it should be in the range of about 20 to about 200 kGy. If the irradiation dose is too low, the stability of the bubbles is not maintained when foamed. If the irradiation dose is too high, the formability of the resulting sheet comprising the foamed composition may be inferior, or the components themselves may decompose. In addition, contained components (such as polymers) may be softened by heat dissipation during electron beam irradiation, so that the sheet may be deformed if the irradiation dose is too high.

  The number of irradiation is preferably 4 times or less, more preferably 2 times or less, and even more preferably 1 time. When the number of irradiations exceeds about 4, the physical properties are undesirably lowered due to excessive strand breakage. In addition, the components themselves are decomposed, and therefore, for example, if foaming is performed, almost uniform bubbles may not be generated in the obtained foamed composition.

  When the thickness of the sheet-like material comprising the component of the foam composition exceeds about 4 mm, irradiating each principal surface of this material with ionizing radiation can reduce the degree of crosslinking of the principal surface (one side or both sides) and the inner layer. It is preferable to make it more uniform.

  Irradiation with an electron beam has the advantage that sheet materials of various thicknesses that comprise the components of the foam composition can be efficiently cross-linked by adjusting the electron acceleration voltage. The acceleration voltage generally ranges from about 200 to about 1500 kV, preferably from about 400 to about 1200 kV, more preferably from about 600 to about 1000 kV. When the acceleration voltage is less than about 200 kV, radiation cannot penetrate and the inner portion of the sheet-like material cannot be crosslinked. As a result, the bubbles in the inner part may become coarse and irregular when foamed. When the acceleration voltage exceeds about 1500 kV, the component itself may be decomposed.

  Regardless of the cross-linking method selected, the cross-linking is carried out so that the total cross-linking degree of the foamed composition is about 20 to about 75%, more preferably about 30 to about 60% as measured by the “Toray gel fraction method”. I do.

  Regardless of the crosslinking method selected, the laminate surface crosslinking is performed so that the laminate surface cross-linking degree of the foamed composition is about 15% to about 65%, more preferably about 25% to about 55%.

  Foaming is usually performed by heating the crosslinked sheet material to a temperature higher than the decomposition temperature of the thermally decomposable foaming agent. For azodicarbonamide (ADCA), which is a thermally decomposable foaming agent, foaming is carried out in a continuous process at about 200 to about 260 ° C, preferably about 220 to about 240 ° C. Usually, foaming is not performed in a batch process. Instead, a continuous process is preferred for the production of foamed compositions or articles incorporating foamed compositions.

  Foaming is usually performed by heating the cross-linked sheet material by molten salt, radiant heater, vertical hot air oven, horizontal hot air oven, microwave energy or a combination of these methods. Foaming is performed by an impregnation step using nitrogen or the like in an autoclave, followed by free foaming using a molten salt, a radiant heater, a vertical hot air oven, a horizontal hot air oven, microwave energy, or a combination of these methods. Also good. It is preferable to heat the cross-linked sheet material using a combination of a molten salt and a radiant heater.

  If necessary, the crosslinked sheet material may be preheated and softened before foaming. Thereby, stabilization of expansion | swelling of the sheet-like material at the time of foaming is accelerated | stimulated.

  The production of the crosslinked foamed composition is usually performed by a multi-stage process including the following steps. 1) mixing / extrusion or mixing / kneading or mixing / calendering of the polymer matrix sheet, 2) crosslinking with a radiation source such as an electron beam, and 3) a) molten salt, radiant heater, hot air oven or B) a foaming step in which the material is heated by microwave energy, or b) an impregnation step using nitrogen in an autoclave followed by molten salt, a radiant heater, a hot air oven or microwave energy.

  A preferred method for producing a foamed composition such as a foamed sheet includes mixing, kneading, extrusion / kneading by extruding, cross-linking by mixing the sheet-like material physically with an electron beam, and mixing. It is preferable to foam the sheet-like material by decomposition of the added organic foaming agent (azodicarbonamide (ADCA)) and to expand by heating with a molten salt and / or a radiant heater.

Preferably, the method for producing the foam composition is a foam having a partial density or “total” density of about 20 to about 250 kg / m ³ , preferably about 50 kg / m ³ to about 125 kg / m ³ as measured according to JIS K6767. It is carried out so as to obtain a composition. The partial density can be adjusted by the amount of the foaming agent. If the density of the foamed sheet is less than about 20 kg / m ³ , the sheet will not foam efficiently due to the large amount of chemical foaming agent necessary to achieve the density. Furthermore, if the density of the foamed sheet is less than about 20 kg / m ³ , it becomes more difficult to control the expansion of the sheet during the foaming process. Therefore, it becomes even more difficult to produce a foam sheet having a uniform partial density and thickness. Furthermore, when the density of the foamed sheet is less than 20 kg / m ³ , the foamed sheet is more likely to collapse.

Preferably, the method for producing the foamed composition has a laminated surface density of about 35 to about 275 kg / m ³ , preferably about 65 kg / m on the 0.45 mm to 0.60 mm side in contact with the support layer, measured according to JIS K6767. ³ to about 140 kg / m ³ of foaming composition are obtained.

The foam composition is not limited to a partial density of about 250 kg / m ³ . While foams of about 350 kg / m ³ , about 450 kg / m ³ or about 550 kg / m ³ may be produced, it is preferred that the foam composition has a density of less than about 250 kg / m ³ .

  The average cell size is preferably about 0.05 to about 1.0 mm, more preferably about 0.1 to about 0.7 mm. When the average cell size is less than about 0.05 mm, the softness, touch and flexibility of the foamed composition are lowered. When the average cell size exceeds 1 mm, the surface of the foamed composition becomes uneven. Also, if the average cell size of the cell population is unfavorable in the stretched area or the part subjected to secondary processing, the foam composition may be undesirably torn. The bubble size in the foam composition is a population of bubbles in the core of the foam composition that is relatively spherical and a population of bubbles in the skin near the surface of the relatively flat, thin and / or rectangular foam composition. A bimodal distribution representing

  The thickness of the foamed composition may be about 0.2 mm to about 50 mm, preferably about 0.4 mm to about 40 mm, more preferably about 0.6 mm to about 30 mm, and about 0.8 mm to about 20 mm. Further preferred. When the thickness is less than about 0.2 mm, the gas loss from the main surface is not extremely efficient. If the thickness exceeds about 50 mm, it becomes more difficult to control the expansion during the foaming process. Therefore, it becomes even more difficult to produce a foamed sheet comprising a foamed composition having a uniform partial density and thickness. Desirable thickness can also be obtained by secondary processing such as slicing, skiving or adhesion. Thickness ranges from about 0.1 mm to about 100 mm can be obtained by slicing, skiving or gluing. The thickness of the support layer such as TPO may be about 0.2 mm to about 1.2 mm.

  The compressive strength of the foamed composition varies depending on the partial density, the type of main polymer resin, and the amount of each main polymer resin in the composition. The compressive strength is measured according to JIS K6767 as described above. Stack 50 × 50 mm pre-cut foam to about 25 mm and compress to 75% of the original stacked height at a speed of 10 mm / min. After maintaining the compressed state for 20 seconds, the compression strength is recorded.

  Polypropylene (one or more) comprising the main polymer resin may be polypropylene or may contain an elastic component (usually an ethylene component). Accordingly, the main polymer is not limited to polypropylene, impact-modified polypropylene, polypropylene-ethylene copolymer, metallocene polypropylene, metallocene polypropylene-ethylene copolymer, polypropylene-based polyolefin plastomer, polypropylene-based polyolefin elastomer plastomer, polypropylene-based polyolefin. It may be selected from elastomers, polypropylene-based thermoplastic polyolefin blends and polypropylene-based thermoplastic elastomer blends.

  The melting temperature of the polypropylene-based material in the present methods and compositions is preferably about 125 ° C or higher, most preferably above about 135 ° C. When the melting temperature of the polypropylene-based material is less than about 125 ° C, good peel tear strength may not be obtained in the support layer / foam laminate composition after heat aging at 120 ° C for 120 hours.

  An example of polypropylene is isotactic homopolypropylene, but other polypropylenes may be used.

  Examples of impact modified polypropylene include homopolypropylene and ethylene-propylene copolymer rubber and ethylene-propylene- (non-conjugated diene) copolymer rubber. Two specific examples are TI4015F and TI4015F2 resins from Braskem PP Americas.

Examples of the metallocene polypropylene include, but are not limited to, metallocene syndiotactic homopolypropylene, metallocene atactic homopolypropylene, and metallocene isotactic homopolypropylene. Examples of metallocene polypropylenes are those marketed under the trade names METOCENE ^™ (Lion del Basel) and ACHIEVE ^™ (ExxonMobil). Metallocene polypropylene is also commercially available from Total Petrochemicals USA and grades include M3551, M3282MZ, M7672, 1251, 1471, 1571 and 1751.

Polypropylene-based polyolefin plastomer (POP) and / or polypropylene-based polyolefin elastomer plastomer is a propylene-based copolymer. Non-limiting examples of polypropylene-based polyolefin plastomer polymers are those marketed under the trade names VERSIFY ^™ (Dow Chemical Company) and VISTAMAXX ^™ (ExxonMobil).

Polypropylene polyolefin elastomer (POE) is a propylene copolymer. Non-limiting examples of propylene-based polyolefin elastomers include THERMORUN ^™ and ZELAS ^™ (Mitsubishi Chemical), ADFLEX ^™ and SOFTELL ^™ (Lion Delbacell), VERSIFY ^™ (Dow Chemical Company), and VISTAMAXX ^™ (ExxonMobil). There is a polymer marketed under the trade name.

The polypropylene-based thermoplastic polyolefin blend (TPO) is a homopolypropylene and / or a polypropylene-ethylene copolymer and / or a metallocene homopolypropylene, both of which are plastomer characteristics and elastomer plastomer characteristics of the thermoplastic polyolefin blend (TPO). Or it may have a sufficient amount of ethylene-propylene (EP) copolymer rubber or ethylene-propylene (non-conjugated diene) (EPDM) copolymer rubber to impart elastomeric properties. Non-limiting examples of polypropylene-based polyolefin blend polymers include EXCELLINK ^™ (JSR Corporation), THERMORUN ^™ and ZELAS ^™ (Mitsubishi Chemical), FERROFLEX ^™ and RxLOY ^™ (Ferro) and TELCAR ^™ (Technol Apex) There is a polymer blend marketed under the trade name

  The polypropylene-based thermoplastic elastomer blend (TPE) is a homopolypropylene and / or a polypropylene-ethylene copolymer and / or a metallocene homopolypropylene, both of which have a plastomer property and an elastomer plastomer property in the thermoplastic elastomer blend (TPE). Alternatively, it may have a sufficient amount of diblock or multiblock thermoplastic rubber modifier (SEBS, SEPS, SEEPS, SEP, SEBC, CEBC, HSB, etc.) to provide elastomeric properties. Non-limiting examples of polypropylene-based thermoplastic elastomer blend polymers include DYNAFLEX® and VERSAFLEX® (GLS), MONPRENE® and TEKRON® (Technol Apex) and There is a polymer blend marketed under the trade name DURAGRIP® (Advanced Polymer Alloys).

  Also, a laminated composition comprising a first layer of foam composition and a second support layer that may be, but is not limited to, a plastomer, elastomer plastomer or elastomeric thermoplastic polyolefin TPO layer. Is provided.

  Such a laminate can be manufactured by well-known standard techniques. The foam of this invention can be laminated | stacked on the single side | surface or both surfaces of a support layer. Additional layers / substrates may also be laminated to the resulting bilayer laminate to suit the selected application.

  The foamed composition or the laminated composition can be suitably used for various applications such as automotive applications. For example, but not limited to automobiles such as door panels, door rolls, door inserts, door stuffers, trunk stuffers, armrests, center consoles, seat cushions, seat backs, headrests, seat back panels, instrument panels, knee bolsters, head liners, etc. Interior parts.

  The foam sheet and laminate composition of the present invention include, but are not limited to, embossing, corona or plasma or flame treatment, roughening treatment, smoothening treatment, perforation treatment or microperforation treatment, splicing, slicing, sky Various secondary processes such as bing, layering, adhesion, and drilling may be performed.

Examples of factors that affect the adhesion / interfacial adhesion strength between the foam composition and a support layer such as TPO include, but are not limited to, the following.
1) Temperature at which the laminated surface of TPO is heated before contacting with foam 2) Temperature at which the laminated surface of polypropylene foam is heated before contacting with TPO 3) Pressure applied to TPO and foam during lamination 4) Component of TPO 5) Component of polypropylene foam 6) Amount and type of physical or chemical cross-linking in TPO 7) Amount and type of physical cross-linking in polypropylene foam 8) TPO and polypropylene foam Compatibility and / or polymer chain entanglement and / or miscibility 9) Roughness or smoothness of TPO laminate (when producing TPO sheet individually)
10) Roughness or smoothness of the laminated surface of polypropylene foam

Some laminators have limited ability to modify the above factors. For example,
1) The lamination device may not be designed to heat the TPO lamination surface and / or the polypropylene foam lamination surface to the most desirable temperature for lamination.
2) The laminator may not be designed to apply the most desirable pressure on the TPO and foam during lamination.
3) Laminators may be limited to certain TPO formulations that are less preferred for high quality adhesion to polypropylene.
4) TPO and foam production equipment is an interior trim production equipment that specifies the amount and type of cross-linking in the TPO and / or polypropylene foam, and may be less preferred for lamination with good quantity and type. It may be limited to a trim manufacturing apparatus.

  As a result, the present inventors have found that there are specific polypropylene foams and polypropylene-polyethylene blend foams that correspond to these limitations and have significantly improved adhesion to a support layer such as TPO. A representative example is shown in Table I. In contrast, the comparative commercially available polypropylene foam and polypropylene-polyethylene blend foam shown in Table II are not desirable in terms of adhesion to TPO.

  Conventional polypropylene foams such as those shown in Table II have good thermoformability required for the production of interior trim panels. However, with these foams, it is difficult to obtain the desired adhesion / interfacial adhesion strength with TPO so as to be suitable for some instrument panel applications, door panel applications, etc. in most lamination processes.

  The foam was laminated in four lamination steps. Different TPO was used in each step.

Lamination process “A”
In the lamination step A, the foam surface is heated before lamination. After extruding TPO directly onto the heated foam, both are pulled and passed through the nip to create a laminate.

The foam evaluated in the lamination step A has a density of about 100 kg / m ³ . The foams of Examples A1 and A2 are 90% polypropylene and 10% CEBC. The foams of Examples A3, A4 and A5 are 70% polypropylene, 20% LLDPE and 10% CEBC. The foam of Example A6 is 62.5% polypropylene and 37.5% VLDPE. The two-layer laminates of Examples A1 to A6 have a blister evaluation of 1, a peel tear strength before aging of about 34 N or more, and a peel tear strength after heat aging of about 28 N or more.

  The foams of Comparative Examples A1 to A5 are 80% polypropylene and 20% LLDPE. The two-layer laminate of Comparative Example A1 has a blister rating of 5, a peel tear strength before aging of less than 34 N, and a peel tear strength after heat aging of less than 28 N. The two-layer laminate of Comparative Examples A2 to A5 has a blister evaluation of 1, a peel tear strength before aging of about 34 N or more, and a peel tear strength after heat aging of less than 28 N.

  From Examples A1 to A5, by using 10% of CEBC instead of PP RCP and / or LLDPE, the adhesive strength between the foam and TPO is increased, and the peel tear strength before aging is about 34 N or more, and after heat aging It has been demonstrated that the peel tear strength is less than 28N.

  From Example A6, by using 10% of VLDPE instead of PP RCP and / or LLDPE, the adhesive strength between the foam and TPO is increased, and the peel tear strength before aging is about 34 N or more, and heat aging It has been demonstrated that the subsequent peel tear strength is less than 28N.

Lamination process “B”
In the lamination step B, the foam surface is not heated before lamination. TPO skins are made individually about one week before lamination. In the lamination step B, after heating the TPO skin, the heated TPO and the unheated foam are pulled together and passed through the nip to create a laminate.

The foam evaluated in the lamination step B has a density of about 100 kg / m ³ . Some of the foams evaluated in the lamination step B were also evaluated in the lamination step A. The foam of Example B1 is 90% polypropylene and 10% CEBC. The foams of Examples B2 and B3 are 70% polypropylene, 20% LLDPE, and 10% CEBC. The bilayer laminates of Examples B1 to B3 have a blister evaluation of 1, a peel tear strength before aging of about 34 N or more, and a peel tear strength after heat aging of about 28 N or more.

  The foams of Comparative Examples B1 and B2 are 80% polypropylene and 20% LLDPE. The two-layer laminates of Comparative Examples B1 and B2 have a blister rating of 1, a peel tear strength before aging of less than 34 N, and a peel tear strength after heat aging of less than 28 N. The two-layer laminate of Comparative Examples A2 to A5 has a blister evaluation of 1, a peel tear strength before aging of about 34 N or more, and a peel tear strength after heat aging of less than 28 N.

  From Examples B1 to B3, by using 10% of CEBC instead of PP RCP and / or LLDPE, the adhesive strength between the foam and TPO is increased, and the peel tear strength before aging is about 34 N or more, and after heat aging It has been demonstrated that the peel tear strength is less than 28N. This result is obtained regardless of the difference in the lamination process and TPO composition.

Lamination process “C”
In the lamination step C, the foam surface is not heated before lamination. TPO skins are made individually about one week before lamination. In the lamination step C, after heating the TPO skin, the heated TPO and the unheated foam are pulled together and passed through the nip to create a laminate.

The foam evaluated in the lamination step C has a density of about 67 kg / m ³ . The foams of Examples C1 to C3 are 80% polypropylene and 20% VLDPE. The bilayer laminates of Examples C1 to C3 have a blister evaluation of 1, a peel tear strength before aging of about 26 N or more, and a peel tear strength after heat aging of about 19 N or more.

  The foams of Comparative Examples C1 and C2 are 80% polypropylene and 20% LLDPE. The foam of Comparative Example C3 is 70% polypropylene, 20% LLDPE, and 10% CEBC. The two-layer laminate of Comparative Example C1 has a blister evaluation of 4, a peel tear strength before aging of about 26 N or more, and a peel tear strength after heat aging of 19 N or more. The two-layer laminate of Comparative Example C2 has a blister evaluation of 5, a peel tear strength before aging of less than 26 N, and a peel tear strength after heat aging of 19 N or more. The two-layer laminate of Comparative Example C3 has a blister rating of 5, a peel tear strength before aging of about 26 N or more, and a peel tear strength after heat aging of less than 19 N.

  From Examples C1-C3, i) 30% impact resistant hPP instead of PP RCP, and ii) 20% VLDPE instead of LLDPE increase the adhesive strength between the foam and TPO before aging. It was demonstrated that the peel tear strength was about 26 N or more, and the peel tear strength after heat aging was about 19 N or more.

  However, unlike the lamination steps A and B, even when 10% of CEBC was used instead of PP RCP (Comparative Example C3), the adhesion between the foam and TPO did not increase dramatically. This is due to the difference in the lamination process and the type of TPO. In this case, CEBC is not very effective in strengthening the adhesion between the foam and TPO.

Lamination process “D”
In the lamination step D, the foam surface is not heated before lamination. TPO skins are made individually about one week before lamination. In the lamination step D, after heating the TPO skin, the heated TPO and the unheated foam are pulled together and passed through the nip to create a laminate.

Foam was evaluated in the laminating step D has a density in the range of from about ^{65kg / m 3 ~84kg / m 3} . The foams of Examples D1 to D3 are 40% polypropylene, 50% OBC, and 10% CEBC. The two-layer laminates of Examples D1 to D3 have a blister evaluation of 1, a peel tear strength before aging of about 17 N or more, and a peel tear strength after heat aging of about 15 N.

The foam of Comparative Example D1 has a density of about 66 kg / m ³ to about 78 kg / m ³ . The foam of Comparative Example D1 is 40% polypropylene and 60% OBC. The two-layer laminate of Example D1 has a blister rating of 1, a peel tear strength before aging of less than 17 N, and a peel tear strength after heat aging of less than 15 N in the machine direction.

  From Examples D1 to D3, by using 10% of CEBC instead of OBC, the adhesive strength between the foam and TPO becomes stronger, the peel tear strength before aging is about 17 N or more, and the peel tear strength after heat aging is 15 N Proved to be less than

Claims (36)

A foamed composition comprising about 50 to about 95 parts by weight of at least one polypropylene polymer having a density of about 85 to about 125 kg / m ³ , having a blister rating of 1 to 2, and aging when laminated to a support layer A composition wherein the previous peel tear strength is at least about 34 N and the peel tear strength after heat aging is at least about 28 N.   The foaming composition according to claim 1, wherein the support layer is TPO.   The foamed composition of claim 1, wherein the polypropylene has a melt flow index at 230 ° C. of about 0.1 to about 25 g / 10 minutes.   The foam composition according to claim 1, further comprising an elastic component.   The foaming composition according to claim 4, wherein the elastic component contains an ethylene component.   The foamed composition of claim 4, wherein the elastic component is blended with the polypropylene polymer.   The foamed composition of claim 4, wherein the elastic component is polymerized with the polypropylene polymer.   6. The ethylene component is at least one selected from the group consisting of LLDPE, CEBC, OBC, EPR, mPP, MPE, EPDM, SEBS, SEPS, SEEPS, SEP, SEBC, HSB and VLDPE. Foaming composition.   The foaming composition according to claim 1, formed from at least one additive selected from the group consisting of a crosslinking agent, a foaming agent, an antioxidant and an antifogging agent.   The laminated body which laminated | stacked the foaming composition of Claim 1 on the said support layer.   The laminate according to claim 10, wherein the support layer is TPO.   The laminate of claim 10, wherein the foamed composition has a thickness of about 0.2 to about 50 mm and the support layer has a thickness of about 0.2 to about 1.2 mm. A foamed composition comprising about 50 to about 95 parts by weight of at least one polypropylene polymer having a density of about 50 to about 85 kg / m ³ , having a blister rating of 1 to 2, and aging when laminated to a support layer A composition wherein the previous peel tear strength is at least about 26 N and the peel tear strength after heat aging is at least about 19 N.   The foaming composition according to claim 13, wherein the support layer is TPO.   The foam composition of claim 13, wherein the polypropylene has a melt flow index at 230 ° C. of about 0.1 to about 25 g / 10 min.   The foamed composition of claim 13 further comprising an elastic component.   The foaming composition according to claim 16, wherein the elastic component contains an ethylene component.   The foam composition of claim 16, wherein the elastic component is blended with the polypropylene polymer.   The foam composition of claim 16, wherein the elastic component is polymerized with the polypropylene polymer.   18. The ethylene component is at least one selected from the group consisting of LLDPE, CEBC, OBC, EPR, mPP, mPE, EPDM, SEBS, SEPS, SEEPS, SEP, SEBC, HSB and VLDPE. Foaming composition.   The foaming composition according to claim 13, formed from at least one additive selected from the group consisting of a crosslinking agent, a foaming agent, an antioxidant and an antifogging agent.   The laminated body which laminated | stacked the foaming composition of Claim 13 on the said support layer.   The laminate according to claim 22, wherein the support layer is TPO.   23. The laminate of claim 22, wherein the foamed composition has a thickness of about 0.2 to about 50 mm and the support layer has a thickness of about 0.2 to about 1.2 mm. A foamed composition comprising from about 30 to about 50 parts by weight of at least one polypropylene polymer having a density of about 50 to about 85 kg / m ³ , having a blister rating of 1 to 2, and aging when laminated to a support layer A composition wherein the previous peel tear strength is at least about 17 N and the peel tear strength after heat aging is at least about 15 N.   26. The foam composition of claim 25, wherein the support layer is TPO.   26. The foam composition of claim 25, wherein the polypropylene has a melt flow index of about 0.1 to about 25 g / 10 min at 230C.   26. The foam composition of claim 25, further comprising an elastic component.   The foaming composition according to claim 28, wherein the elastic component contains an ethylene component.   29. The foam composition of claim 28, wherein the elastic component is blended with the polypropylene polymer.   29. The foam composition of claim 28, wherein the elastic component is polymerized with the polypropylene polymer.   30. The ethylene component is at least one selected from the group consisting of LLDPE, CEBC, OBC, EPR, mPP, mPE, EPDM, SEBS, SEPS, SEEPS, SEP, SEBC, HSB and VLDPE. Foaming composition.   26. The foam composition of claim 25, formed from at least one additive selected from the group consisting of a crosslinking agent, a foaming agent, an antioxidant and an antifogging agent.   A laminate in which the foam composition according to claim 25 is laminated on the support layer.   The laminate according to claim 34, wherein the support layer is TPO.   35. The laminate of claim 34, wherein the foamed composition has a thickness of about 0.2 to about 50 mm and the support layer has a thickness of about 0.2 to about 1.2 mm.